JPH06303723A - Voltage monitor - Google Patents

Abstract

PURPOSE:To rapidly stop an operation output of a VQC by detecting an abrupt rise or fall of a bus voltage by an overvoltage detector and an insufficient voltage detector, and locking the output of the VQC. CONSTITUTION:Primary, secondary bus voltages input to an apparatus are converted to a mean voltage among three phase lines by an A/D conversion and voltage calculator 2, and then input to digital overvoltage relays 1A, 1A' and digital insufficient voltage relays 1C, 1C'. A malfunction cause is identified by an operation of a voltage relay at the time of a malfunction of the bus voltage to lock excess application or excess opening of a phase modifying facility such as a power capacitor SC and a shunt reactor ShR, etc., or an unnecessary tap operation of a transformer LR, and in order to prevent a further variation in primary, secondary bus voltage, a lock signal to a VQC is output. As a result, since the operation output of the VQC can be rapidly stopped against an abnormal changes of the primary, secondary bus voltages, a stable power can be supplied.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention detects abnormalities in primary and secondary bus voltage of a substation and detects the voltage / voltage installed in the substation.
The present invention relates to a voltage monitoring device for controlling stoppage of a reactive power adjusting device.

[0002]

2. Description of the Related Art In general, as shown in FIG. 1, voltage / reactive power control in a substation employs voltage priority control from the viewpoint of stable power supply to consumers.
The adjustment of the secondary and secondary bus voltages and the passing reactive power to appropriate values is performed by a microcomputer-based "voltage and reactive power adjusting device" (hereinafter referred to as "VQC").
Control of voltage / reactive power by such VQC (not shown) is performed by tap switching operation of load tap switching transformer (LR) and turning on / off of power capacitor (SC) or shunt reactor (ShR). Since the voltage change due to one of these operations is stepwise, VQ when there is an abnormal change in the bus voltage is
Unnecessary operation of C causes a steep rise or fall of the primary and secondary bus voltages, and there is a risk of causing various failures. In other words, if the primary and secondary bus voltage rises significantly, there is a risk of causing burnout of power equipment and customer equipment,
In addition, if the primary and secondary bus voltage drops significantly, wide-range power outages may occur due to load adjustment.

A conventional voltage monitoring device is a primary or secondary transformer in a substation.
Detects a sudden rise or fall of the next bus voltage and detects VQC
The operation output of (not shown) is stopped to prevent further rapid change in bus voltage. Then, when the primary and secondary bus voltages return to within a predetermined constant value, the operation output of VQC is restarted.

[0004]

Such a conventional voltage monitoring device detects a sharp rise or fall of the primary and secondary bus voltage of a substation by a voltage detector (PD / PT), and By operating the voltage detector (relay) to alert and display the operator at the substation, the operator can perform VQ
Since the VQC is stopped after determining whether it is due to a malfunction of C or due to other factors such as a system accident, if the voltage change is fast, it will not be in time and the above-mentioned various troubles will be caused. There was a risk.

The present invention has been made in view of the above points, and an abnormal change in the bus voltage is V regardless of an artificial operation.
(EN) Provided is a voltage monitoring device capable of promptly stopping the operation output of VQC by determining whether it is due to QC.

[0006]

[Means and Actions for Solving the Problems] A rapid rise or fall of the bus voltage is detected by an overvoltage detector and an undervoltage detector, and a load tap switching transformer, a power capacitor, a shunt reactor, etc. are adjusted. By locking the operation output of the VQC that performs voltage / reactive power adjustment control by operating the phase equipment, it is possible to prevent further changes in the bus voltage, and the bus stop detector detects the stop of the bus and By prohibiting the lock of the VQC operation output, it is possible to maintain the condition of the load tap switching transformer, power condenser, shunt reactor, and other phasing equipment in the state before the bus was stopped, and the bus was restored. Sometimes proper bus voltage is obtained.

[0007]

FIG. 2 shows an embodiment of the voltage monitoring equipment of the present invention.

In FIG. 2, 1A and 1A 'are overvoltage relays,
1B and 1B ′ are undervoltage relays, 1C and 1C ′ are bus stop voltage relays, and 1N are digital signal processing devices (DI circuit (12), DO circuit (8), etc.) in the voltage monitoring circuit. Status detection relay, 1X is the undervoltage (DC voltage) relay monitoring the control power supply in the substation, 2 is the primary detected by the transformer for the instrument (Fig. 2, PD, PT),
It is an A / D converter / arithmetic unit for A / D converting the secondary bus voltage and calculating the average voltage between three phases. Also, 3A, 3A '
Is an overvoltage auxiliary relay that operates when the bus voltage abnormally rises, 3B and 3B 'are auxiliary relays that operate when the bus voltage abnormally drops, 3N is an auxiliary relay for the status detection relay (1N), and 3X is the shortage Auxiliary relays 3a, 3a ', 3b, 3b', 3x, 3x 'of the voltage relay (1X) are contacts of the auxiliary relays, 4A, 4A', 4B, 4B ', 4C, 4C' are 0-5 respectively. Timer for malfunction prevention that can be set to (seconds), 5,
5'is, for example, a malfunction prevention timer settled at 20 milliseconds,
6,6 'are AND circuits with prohibited input terminals, 7A, 7A', 7B, 7
B'is an OR circuit, and 8A, 8A ', 8B, 8B', 8N 'are digital output circuits which are buffer circuits. Further, 9A, 9A ', 9B and 9B' are buffer circuits for monitoring the contacts of the auxiliary relay, 10 is an output signal terminal for alarm / display, and 10A, 10A ', 10B and 10B' are the voltage monitoring devices respectively. To a VQC (not shown) is an output signal (lock signal) terminal. 11 is a DC / for monitoring the control power supply voltage.
The DC converter 12 is a digital input circuit of the output contact monitoring device (13) for monitoring the output contacts 3a, 3a ', 3b, 3b' and is composed of a buffer circuit.

The operation of this voltage monitoring device will be described below with reference to the substation shown in FIG.

The voltage monitoring apparatus shown in FIG. 2 monitors the bus voltage of both the instep bus and the O-bus, and locks and stops the operation output of VQC (not shown) when there is an abnormality. However, since the voltage monitoring of the upper bus and the voltage monitoring of the second bus have the same operation, only the operation of voltage monitoring of the first bus will be described.

The primary (secondary) bus voltage and the secondary (secondary) bus voltage at the substation (in operation of the main bus) shown in FIG. 1 are respectively converted into a capacitor type transformer (PD) for a meter and a transformer (P) for a meter.
T) and input into the voltage monitoring device shown in FIG. The input primary and secondary bus voltage is converted to a three-phase line average voltage (digital value) by the A / D conversion and voltage calculator 2 and then digital overvoltage relay (1A, 1A ') digital undervoltage Input to the relays (1B, 1B ') and digital bus stop voltage relays (1C, 1C'), and determine the cause of abnormality by the operation of those voltage relays when the bus voltage is abnormal, and then the power capacitor (SC) And, lock up the excessive tapping or over-opening of phasing equipment such as shunt reactor (ShR) or unnecessary tap operation of the transformer (LR) to prevent further fluctuation of primary and secondary bus voltage. Therefore, a lock signal to VQC (not shown) is output.

Hereinafter, a case where the bus voltage is abnormal will be individually described.

(1). Primary bus voltage / overvoltage When the primary bus voltage rises above a specified value, an overvoltage relay
It is detected as an overvoltage by (1A), and the overvoltage auxiliary relay (3A) is energized via the malfunction prevention timer (4A) and the OR circuit (7A). The b contact (3a) of the auxiliary relay (3A) is opened by the operation of the auxiliary relay (3A), and the power capacitor (SC)
The lock signal (10A) that locks the input of the shunt and the opening of the shunt actuator (ShR) is output to VQC (not shown),
The automatic operation of the QC can be locked to prevent the primary bus voltage from further increasing. At the same time, overvoltage auxiliary relay
The contact (3a) of the contact (3a) is closed by the operation of (3A), and an alarm / display signal (10) is output, and the state of these contacts (3a) is output via the buffer circuit (9A, 12). Monitor according to (13).

(2). Primary bus voltage / undervoltage When the primary bus voltage drops below a predetermined value, it is detected as an undervoltage by the undervoltage relay (1B), and the malfunction prevention timer (5, 4B), AND circuit (6) and OR circuit Undervoltage auxiliary relay (3B) is energized via (7B). The b contact (3b) of the auxiliary relay (3B) is activated.
Opens, a lock signal (10B) that locks the opening of the power capacitor (SC) and the closing of the shunt reactor (ShR) is output to the VQC (not shown), and the automatic operation of the VQC is locked to It is possible to prevent the bus bar voltage generator from further lowering. At the same time, the operation of the undervoltage auxiliary relay (3B) closes its a-contact (3b) and outputs an alarm / display signal (10), and the state of those contacts (3b) is also controlled by the buffer circuit (9B, 12). Via the output contact monitoring device (13).

(3). Secondary bus voltage / overvoltage When the secondary bus voltage rises above a specified value, an overvoltage relay
It is detected as an overvoltage by (1A '), and the overvoltage auxiliary relays (3A, 3A') are energized via the malfunction prevention timer (4A ') and the OR circuit (7A, 7A'). The auxiliary relay
By actuation of (3A, 3A '), their b contacts (3a, 3a')
Opens, and the lock signal (10A) that locks the input of the power capacitor (SC) and the opening of the shunt reactor (ShR) is V
The QC (not shown) is output to lock the automatic operation of the VQC, and the lock signal (10A ') that locks the tap-up operation of the tap change transformer (LR) under load is output to output the secondary bus voltage. It is possible to prevent further increase of

At the same time, the operation of the overvoltage auxiliary relay (3A 3A ') closes the contacts (3a, 3a') of the alarm /
In addition to outputting the display signal (10), those contacts (3a, 3)
The state of a ') is monitored by the output contact monitoring device (13).

(4). Secondary bus voltage / undervoltage When the secondary bus voltage drops below a predetermined value, it is detected as an undervoltage by the undervoltage relay (1B '), and the malfunction prevention timer (5', 4B ') and AND circuit (6') are detected. ) And OR circuit
Undervoltage auxiliary relay (3B, 3B ') via (7B, 7B')
Is activated. By the operation of the auxiliary relays (3B, 3B '), their contacts (3b, 3b') are opened, and the closing lock signal (10B) for locking the opening of the power capacitor (SC) and the closing of the shunt reactor (ShR). ) Outputs to VQC (not shown), locks the automatic operation of the VQC, and outputs the lock signal (10B ′) that locks the tap down operation of the load tap switching transformer (LR). Further lowering of the secondary bus voltage can be prevented.

At the same time, the undervoltage auxiliary relay (3B, 3B ')
By the operation of, those a contacts (3b, 3b ') are closed, an alarm / display signal (10) is output, and the contacts (3b, 3b,
The state 3b ') is monitored by the output contact monitoring device (13).

As described above, the overvoltage auxiliary relay (1A, 1A) or the undervoltage relay (1B, 1B ') detects the abnormality of the primary and secondary bus voltage, and the VQC (not shown) is almost instantaneously detected. By locking the automatic operation, it is possible to suppress further fluctuations in the primary and secondary bus voltage due to unnecessary operation of VQC.

Even while the automatic operation of VQC is locked, the phase-adjustment equipment such as the load tap switching transformer (LR), the power capacitor (SC), and the shunt reactor (ShR) are not available. Manual operation is possible.

Next, due to factors such as a power system accident, 1
When the secondary and secondary bus voltage drops sharply, the bus stop voltage relay (1C, 1C ') detects that state and
An undervoltage auxiliary relay by the output of the undervoltage relay (1B, 1B ') that detects a sudden drop of the bus voltage at the same time by giving a signal to the inhibition input terminals of the ND circuit (6, 6')
Block the operation of (3B, 3B '). This means that by inserting a delay circuit (for example, timer 5, 5 ') into the output of the undervoltage relay (1B, 1B'), the bus stop voltage relay
The output of (1C, 1C ') is the undervoltage relay (1B, 1B')
Since it can be applied to the prohibition terminals of the AND circuit (6, 6 ') faster than the output of and the operation of the undervoltage relay (3B, 3B') can be prevented without malfunction, when the power system is restored, the load This is to keep the state of the phase-adjusting equipment such as the time tap switching transformer (LR), the power capacitor (SC), and the shunt reactor (ShR) in the normal state.

[0022]

As described above, according to the present invention, the VQC operation output can be promptly stopped in response to an abnormal change in the primary and secondary bus voltage in the substation.
Not only does not give further voltage change due to unnecessary operation of VQC at abnormal time, but when abnormal voltage change is restored, tap change transformer (LR) at load, power capacitor (SC), shunt reactor The state of the phase adjusting equipment such as (ShR) can be maintained in a state under normal load, and stable power supply to consumers can be performed.

[Brief description of drawings]

FIG. 1 is a substation to which the voltage monitoring device of the present invention is applied.

FIG. 2 is an embodiment of the voltage monitoring device of the present invention.

[Explanation of symbols]

 1A, 1A 'Overvoltage relay 1B, 1B' Undervoltage relay 1C, 1C 'Bus stop voltage relay 2 A / D converter / calculator 3A, 3A' Overvoltage auxiliary relay 3B, 3B 'Undervoltage auxiliary relay 4A, 4A'4B, 4B'4C, 4C 'Malfunction prevention timer 5,5' Delay circuit (eg timer) 6,6 'AND circuit with inhibit input terminal 7A, 7A' 7B, 7B 'OR circuit 10A, 10A'10B, 10B' VQC Operation lock signal 10 Alarm / display signal

Claims (2)

[Claims] 1. The power is received from the primary bus, and voltage / reactive power adjustment control is performed by a load tap switching transformer, a power condenser, a shunt reactor, and other phase adjusting equipment to distribute the power to the secondary bus. A voltage monitoring device for the voltage / reactive power adjustment control in a power substation, comprising: a first overvoltage detector, an undervoltage detector, and a bus stop detector for detecting the primary bus voltage; A second overvoltage detector, an undervoltage detector, and a bus stop detector for detecting a next bus voltage; and an output of the first undervoltage detector,
First AND with the output of the bus stop detector of
A circuit and the output of the second undervoltage detector as an input,
Second AND with the output of the bus stop detector of
A circuit, a first OR circuit that receives the output of the first overvoltage detector and the output of the second overvoltage detector, the output of the first AND circuit, and the second AND circuit A second OR circuit that receives the output of the circuit and a third OR circuit that receives the output of the second overvoltage detector
Circuit, a fourth OR circuit that receives the output of the second AND circuit as an input, and a lock signal that locks the voltage / reactive power adjustment control by the phase adjusting equipment by the outputs of the first and second OR circuits. And a second lock signal output means for obtaining a lock signal for locking the tap switching operation of the tap switching transformer under load by the outputs of the third and fourth OR circuits. A voltage monitoring device comprising: 2. A voltage monitoring device comprising: the outputs of the first and second undervoltage detectors being input to the first and second AND circuits via a delay circuit.